Electrostatically charged biocidal media and applications therefor

ABSTRACT

There is provided a protective media and a method of manufacturing the same. Also provided is a wound dressing, clothing and liners incorporating the protective media and methods of manufacturing the same. In one aspect, the protective media includes a porous dielectric carrier, an active agent incorporated in the porous dielectric carrier, and an electrostatic charge across at least a portion of the porous dielectric carrier. This innovative media is capable of eradicating microorganisms and/or toxins more efficiently than prior art solutions and can also self-sterilize.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of pending U.S. application Ser. No.10/528,005, filed on Mar. 16, 2005, which is a 371 national phaseapplication of PCT/IB03/04553, filed on Sep. 8, 2003, which claims thebenefit of priority to U.S. Provisional Application Nos. 60/411,006,60/434,526 and 60/458,800, filed on Sep. 16, 2002, Dec. 19, 2002 andMar. 28, 2003, respectively, the contents of each are herebyincorporated by reference herein in the entirety.

FIELD OF THE INVENTION

The present invention relates to electrostatically charged filter mediaand more particularly to an electrostatically charged media with anactive agent incorporated thereon, and a method of making the same.

BACKGROUND OF THE INVENTION

Prior art filter methods include, for example, mechanical filtration—aphysical retention of particles larger than the pores of the filtermedia; electrostatic filtration—adhering particles to fibers in thefilter without killing/deactivating the particles; and filtration astaught and claimed in U.S. Pat. No. 5,980,827 which issued to theinventor hereof on Nov. 9, 1999 and is entitled “Disinfection Of AirUsing An Iodine/Resin Disinfectant.” It has been determined thatimproved iodinated resin filtration occurs in a thin media when theproduct is incorporated to a media with a convoluted pathway. By forcingthe microorganism/toxin to pass through a circuitous route, themicroorganism/toxin is eventually killed/deactivated. One method forproviding a circuitous route is to employ a nonwoven media.

In published U.S. patent application number 20010045398 entitled“Process For The Immobilisation Of Particles In A Three DimensionalMatrix Structure” the non-woven material is first produced and then aniodinated resin, such as the one disclosed in U.S. Pat. No. 5,639,452(the '452 patent) is added using alcohol or a partial solvent with ahigh pulsation vacuum pump that opens the filter pores so that theactive agent will go through it (the “Triosyn” resin). The contents ofthe '452 patent is incorporated by reference in its entirety herein.

U.S. Pat. No. 6,346,125 teaches incorporating an aqueous antimicrobialagent into a non-electrostatically charged non-woven material.Specifically, the '125 patent describes a particular process forincorporating an aqueous antimicrobial agent into anon-electrostatically charged non-woven. However, without theelectrostatic properties, the non-woven must be of greater thickness sothat the microorganism has sufficient contact time with theantimicrobial agent for decontamination.

U.S. Pat. No. 5,952,092 teaches a non-woven fabric with chemicallyactive particles. However, this patent does not teach using anelectrostatic substrate as in the present innovation.

Nonwoven electrets and methods of manufacturing the same are known inthe art. For example, U.S. Pat. No. 5,409,766 describes a nonwovenfabric in an electret state composed of monofilaments formed of apolymer composition capable of dust collection over a prolonged time andin a hot and humid condition. Also disclosed are processes for producingthis nonwoven fabric, as well as a filtering air masking materialcomposed of that nonwoven fabric. However, this prior art system doesnot provide antimicrobial/antitoxin properties. Thus, themicroorganism/toxin, while suspended within the nonwoven fabric, is notsterilized or deactivated. Once the electrostatic properties of thenonwoven are depleted or the material is saturated, themicroorganism/toxin may be released back into the atmosphere.

Electrostatically charged filters are known to be used in facemasks, forexample. With respect to both, one of the problems of face seal is wellknown and represents a limitation that the industry has been trying toaddress. The problem resides in the fact that from one morphologicalphysical structure of a human being or structure to the next thedifferences generate such a wide spectrum of geometrical deviations thatit has been difficult to create a 100% airtight seal. For a facemask thedifficulty in creating a seal occurs between the skin and the mask for arange of face sizes and shapes. Various different technological meanshave been tried, for example using, adhesive seals, flat and wide sealsand resilient material seals. The industry has oriented its work oncreating an airtight seal, however, the pressure differential generatedactually forces air in the gaps between seal and skin thus bypassing theair filter material. The electrostatic filter of the present inventionmay be made of a spongy or other breathable nonwoven material so as tominimize the pressure differential, thus preventing air from beingforced through the gaps. Further, it effectively makes the gasket usedto create a closure between the user and the facemask out of a thinfilter having a low-pressure drop like the electrostatic filter andhaving the added benefit of the active agent incorporated thereon.

Other known prior art that teach the use of high pressure drop mediaincludes the mechanical filtration of the HEPA filter. However, thepressure drop of the present invention is approximately 50% to 90% lowerthan that of the HEPA filter alone. The filter further includes amaterial that kills on passage vegetative bacteria, spores, and viruses.They are filtered out of the airstream and are killed. In addition, thepresent invention is self-sterilizing, meaning that not only does itfilter air passed there through, it kills the bacteria trapped on thefilter. Therefore, the media protects both the user and the outside air.

Given the shortcomings of the prior art, it is advantageous to have anelectret, which has improved characteristics over known solutions. Thepresent innovation comprises a substrate that supports an active agentand is a dielectric.

SUMMARY OF THE INVENTION

The present invention overcomes the aforementioned problems of the priorart. Specifically and in accordance with one aspect of the presentinvention, there is provided herein an electrostatically chargednon-woven media that has active agents incorporated therein. Thisinnovative media is capable of eradicating microorganisms and/or toxinsmore efficiently than prior art solutions and can also self-sterilize.

The present invention additionally provides for methods of making theelectrostatically charged filter media having an active agentincorporated therein. The substrate may be manufactured according tovarious methods; the active agent may be incorporated according tovarious methods; and the electrostatic charge may be provided accordingto various methods, all of which are described herein or are known inthe art.

Because substantially less active agent is used for each filter costsare reduced while maintaining effectiveness. Additionally, the enhancedelectrostatic filter of the present invention provides added performanceof the active agent and electrostatic properties.

In addition to the above aspects of the present invention, additionalaspects, features and advantages will become better understood withregard to the following description in connection with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts aspects of an exemplary embodiment of the presentinvention in accordance with the teachings presented herein.

FIGS. 2 and 3 depict exemplary embodiments of electrostatically chargedsubstrates.

FIG. 4 depicts an exemplary embodiment for providing a nonwoven mediawith an active agent incorporated thereon.

DETAILED DESCRIPTION OF THE INVENTION

The following sections describe exemplary embodiments of the presentinvention. It should be apparent to those skilled in the art that thedescribed embodiments of the present invention provided herein areillustrative only and not limiting, having been presented by way ofexample only. All features disclosed in this description may be replacedby alternative features serving the same or similar purpose, unlessexpressly stated otherwise. Therefore, numerous other embodiments of themodifications thereof are contemplated as falling within the scope ofthe present invention as defined herein and equivalents thereto.

The present invention provides an electrostatically charged filter mediacomprising a substrate with an active agent incorporated therein.

Filter Media

The filter media of the present invention includes (1) a substrate, (2)an active agent incorporated therein and (3) an electrostatic charge.

Substrate

The substrate comprises any material having dielectric properties orcapable of being enhanced to have dielectric properties and which iscapable of having an active agent incorporated therein.

In a particular embodiment, the substrate may be a fiber based materialhaving a fibrous matrix structure; it may be a sponge like material havean open cell matrix structure; it may be flexible or inflexible; etc.

As stated above, in one embodiment, the substrate is a nonwoven fabric.Nonwoven is a type of fabric that is bonded together rather than beingspun and woven into a cloth. It may be a manufactured sheet, mat, web orbatt of directionally or randomly oriented fibers bonded by friction oradhesion; it may take the form of a type of fabric. FIG. 1 is providedas an exemplary embodiment of a nonwoven fabric.

In another embodiment, the substrate may be a nonwoven textile ofvarying fluffiness, comprising polymer fiber. The polymer may be forexample, nylon, polyethylene, polypropylene, polyester, etc. or anyother polymer suitable for a filter substrate. Additionally, thesubstrate can be made of materials other than polymer fiber.

The nonwoven material may be of a type suitable for a high efficiencyparticulate air filter (i.e. a HEPA filter). A suitable nonwovenmaterial may be obtained from Technol Aix en Provence Cedex 03 France(see Canadian patent no. 1,243,801); another suitable material may alsobe obtained from Minnesota Mining & Manufacturing Co. (3M). The nonwovenmaterial has a three dimensional structure which should be configured insuch a fashion as to provide a matrix capable to entrap (i.e.physically) the desired active agent. For example if the nonwovenmaterial is based on fibers, the structural fibers of the nonwovenmaterial may be present and distributed in such a fashion as to providea fibrous matrix structure able to entrap the desired active agent. Thenonwoven material may have a microstructure. In a particular embodiment,the active agent has a size appropriate to be entrapped by the threedimensional (e.g. web) matrix structure of the desired nonwovenmaterial.

Alternative substrates may further include glass fibers and fibers, suchas cellulose, that are ultimately formed into a paper-based filtermedia. Any substrate capable of acting as carrier for the active agentand having dielectric properties or capable of having dielectricproperties imparted to it, would be a suitable substrate for the presentinvention. When substrates that do not have strong dielectric propertiesare used, such as glass fibers, additives may be provided to improve thedielectric properties of the substrate. The present invention is notlimited to a nonwoven material. Other suitable substrates may includespongy materials or foam.

Active Agent

The active agent of the present invention may be, for example, anantimicrobial, an antitoxin, or the like. The antimicrobial may bebiostatic and/or biocidal. Biostatic is a material that inhibits thegrowth of all or some of bacteria spores, viruses, fungi, etc. (havingbioactive particles), and a biocidal is a material that kills all orsome of bacteria spores, viruses, fungi, etc. Preferably, the biocidalcomprises the iodinated resin particles, such as those described abovein the '452 patent, as described above. Other suitable active agentsinclude silver, copper, zeolyte with an antimicrobial attached thereto,halogenated resins, and agents capable of devitalizing/deactivatingmicroorganisms/toxins that are known in the art, including for exampleactivated carbon, other metals and other chemical compounds. Forexample, a non-exhaustive list of suitable metals and/or chemicalcompounds is as follows:

Exemplary Metals

Aluminum

Barium

Boron

Calcium

Chromium

Copper

Iron

Magnesium

Manganese

Molybdenum

Nickel

Lead

Potassium

Silicon

Sodium

Strontium

Zinc

Exemplary Chemical Compounds

N-methyl piperazine

Potassium Hydroxide

Zinc Chloride

Calcium chloride

Mixture of Sodium carbonate and sodium bicarbonate

Reference in the specification to antimicrobial is used for ease ofreading and is not meant to be limiting.

Electrostatic Charge

The filter media with an active agent incorporated thereon is alsoelectrostatically charged. Accordingly, there is a potential across thesurface(s) of the media creating a field wherein the field can attractand/or repel charged particles introduced to the media so that in someinstances it alters the path of travel of the charged particles.

FIGS. 2-3 provide exemplary representations of electrostatically chargedmedia. Electrostatically charged filter media of the present inventionmay, for example, be single or multi-layered. Each layer may beindividually charged. A single layered media can have a positive chargeon one side and a negative charge on the other. An example of amulti-layered media is a double-layered media. Preferably, a doublelayered media is used wherein the double-layered media comprises twolayers, each being positively charged on one side and negatively chargeon the other side, wherein the two layers are separated by an airspaceand the two layers are oriented so that the negative side of one of thetwo layers is closest to the positive side of the other layer. In thistwo-layer embodiment, the air space increases the net dielectricconstant of the electrostatically charged filter media.

Preferably, a high dielectric constant is provided to maintain thecharge for an extended period of time. For example, air provides a gooddielectric constant, as can be employed in an airspace as describedabove. Thus, the present invention may be effective even when wet or ina humid environment.

The resulting media is an insulating carrier with an active agentadhered thereto or impregnated therein and having an electrostaticcharge. The media according to the present invention can be produced ofdifferent thickness, density and pressure drop. The media describedherein can be used in, for example:

clothing, wound dressings, air filters, shelters, liners and generally,any filter material.

Method of Manufacturing

The present invention additionally provides for a method ofmanufacturing the electrostatically charged filter media having anactive agent incorporated thereon. The substrate itself may bemanufactured according to various known methods, such as melt blown,spun blown, air laid, carted, etc.

Method of Incorporating the Active Agent

Prior art incorporation methods using polypropylene require the use ofpolyethylene to maintain a tackiness to the fibers to hold the solidparticulate for a longer amount of time to prevent the particulate fromfalling off the fibers. In the present invention, the active agent, suchas the iodinated resin disclosed in the '452 patent, may be physicallyentrapped in the fibers. Thus, the active agent does not have to adhereto the fibers to be incorporated into the media.

In the present invention, the active agent may be incorporated to thesubstrate according to various methods. For example, liquidemulsification of the active agent in the melt at increased temperatureand increased pressure for mix and melt processes, or incorporation byspraying the active agent after extrusion of non-woven fibers duringprocessing.

In a preferred embodiment, as shown in FIG. 4, polymer granules, such aspolypropylene granules, are extruded through an extruder; the extrudedfibers being of varying thickness and length. As the fibers are extrudedthey fall toward a collecting web. A desired active agent is provided ina cloud at a location closest to the extrusion point of the resultingfibers. The cloud envelops the cooling fibers while the fibers are stillin a quasi-liquid quasi-solid state. In one embodiment, the active agentparticulate may range from 0.2 microns to 0.5 millimeters. However, oneof ordinary skill in the art can apply active agents with smaller andbigger particulates size. The active agent particulate settles andcollects so that it is intermeshed or entrapped with the fibers on thecollecting web. After the fibers with the active agent incorporatedthereon falls to the collecting web, the resulting media is formed intoa mesh by known methods. Additionally, the cloud may be in variousphysical states including a vapor, fine dry dust, or atomized oraerosolized particulate. Advantageously, cloud incorporation may occurat room temperature with particulate also at room temperature. Further,the thickness, length and pressure define the mechanical properties ofthe resulting media.

A suitable melt blown system for the above embodiment is the Accuwebprovided by Accurate Products Co. of Hillside, N.J.

Various other methods of incorporating an active agent to a filter mediaare suitable for the present invention. First, for example, using themethod disclosed in published U.S patent application number 20010045398A1. Second, soaking a bail of hair-like extruded fibers in an activeagent (and using alcohol to achieve the soak) and then creating the feltusing pressure and temperature. Third, taking solid polymer granulesmanufactured with an active agent mixed in an extruder hopper to createa mixture that is then extruded into fine hair-like bails. Felt is thenformed through a temperature and pressure process. Fourth, extruding asubstrate, such as a polymer in to a hair-like substance on to which anactive agent is sprayed in solid after the extrusion. The active agentmay be vaporized like an aerosol. Fifth, the active agent can beinjected or sprayed into non-woven fabric as the fabric is beingpressurized. Sixth, carting bails of filament and mixing the resultingmedia with the active agent to generate a sheet having the active agentincorporated therein. Seventh, depositing the active agent on anon-woven media and thereafter needle-punching the media to impregnatethe active agent through and through the media. Other methods may beused.

In another embodiment of the present invention, polymer granules areplaced in a hopper of an extruder with active agent in dust form priorto extrusion. Thus, the active agent is mixed in the hopper prior to themelt. The two components are mixed, heated and then extruded to form athin “hair” fiber used to make a felt. The resulting hair in the aboveembodiments having the active agent incorporated thereto is a bail-likewool. The substrate could be transparent depending on the polymer used.Additionally, a resulting polymer fiber having the active agentincorporated thereto can be treated with water, pressurized and thenheated to form a felt. In other embodiments, the resulting polymer fiberhaving the active agent incorporated thereto can an be air laid, vacuumlaid, water laid, etc.

Although not specifically described herein, other conventional or knownmethods that achieve incorporation of an active agent to a substrate aresuitable for the present invention. Thus, at this point the substratehas an active agent incorporated therein.

Method of Electrostatically Charging

The substrate having an active agent incorporated therein is providedwith an electrostatic charge. The charge may be induced by using acorona, needle punching, chemical enhancement, any other known chargeinducing system or method, or a combination of any of the foregoing.Needle punching creates high-level friction thus adding a charge.

In a particular embodiment, to make the electrostatically chargednon-woven fabric the formed media, such as felt, is placed into a coronasystem of about 25 Kv, slow pass, until fully charged. The resultingmaterial holds its charge for between about 6 months to 2 years.

Operation of an Electrostatic Filter Media

In operation, a contaminated air or fluid stream is introduced to afilter employing the electrostatically charged filter media of thepresent invention. The air/fluid stream may be forced or drawn throughthe filter media by means of a pressure gradient. The stream may containcontaminant particles of various sizes to be removed or treated by thefilter element. As the stream approaches the filter media, it isdirected through the filter media such that the contaminate particlesare brought into contact with the filter media and removed from thestream or treated by the active agent as describe elsewhere in thisapplication. This is achieved through the properties of the filter,which causes the particles to follow a convoluted pathway through thefilter element, thus increasing the time that the contaminant is incontact with the active agent. This increased contact time increases theeffectiveness of the active agent in treating the particles in thestream.

The convoluted path that the particles follow is the result of the addedelectrostatic properties and the nonwoven properties of the substrate ofthe filter element. With respect to the electrostatic properties of thefilter element, the convoluted pathway of the contaminant particles maybe attributed to the particles polar nature. Polar molecules areneutrally charged and are also large in size. Because of the large size,the contaminants have a magnetic moment, which when subjected to anelectric field causes the contaminant particle to be diverted from itspathway.

Additionally, the convoluted path of the contaminant particles isattributable to the nonwoven properties of the filter substrate. This isachieved because the nonwoven substrate had no direct and continuouspathway for the stream to pass through. Instead, due to the nonwovenproperties, the substrate is made up of a porous material wherein nosingle pores of the material forms a continuous pathway through thesubstrate. Therefore, the stream and the particles carried by the streamare continuously diverted through the substrate.

Accordingly, the travel time through the filter is lengthened and theexposure to the active agent is increased.

Additional Uses

The present invention can also be used in a manner consistent withexisting nonwoven fabrics. Uses in various goods include both durableand disposable goods. For example, nonwovens can be used products suchas diapers, feminine hygiene, adult incontinence, wipes, bed linings,automotive products, face masks, air filtration, water filtration,biological fluids filtration, home furnishings and geotextiles. Themedia described herein can also be used in, for example: clothing, wounddressing, air filter, shelters, and liners. Additional uses includethose known in the art for electrostatic filters and antimicrobial orantitoxin filters.

In a particular embodiment, the filter media according to the presentinvention with or without the active agent can be used as a closure orto make a filter closure for air filters for products such as facemasksand HVAC. According to the present invention there is provided a closurematerial made of substrate having electrostatic properties and anelectrostatic material with an active agent incorporated therein, wherethe material is a high loft (in one embodiment, approximately, 1″ thick)breathable material of a tri-dimensional structure and is placed aroundthe mask or air filter in order to not create a so-called airtightjunction but instead creates a breathable closure that actually coversall the contours of the different geometrical surface to provided apermeable closure, having filtering properties. This approach makes theclosure into a filter whereby air that bypasses the mask through gapscaused by a non-perfect fit, still passes through the closure and isfiltered. In addition, contrary to a “resilient” closure the pressuredifferential that is detrimental in an airtight approach is reversed inour approach since the air following the path of least resistance willpass through the filter material of the mask instead. This method ofclosing a facemask or other filter type could also be achieved with asubstitution of the non-woven filter element with a breathable foamhaving the same properties. Thus, while prior art facemask attempt toblock air flow at the closure, the facemasks of the present inventionacts as a gasket that allows air there through and kills the spores,virus, bacteria, fungi, etc. traveling through the airstream with aneffective active agent, such as the iodinated resin disclosed in the'452 patent, described above. Additionally, the use of straps to holdthe mask in place compresses the gasket of the present invention to fitessentially all faces.

Experimental Data

Experimental tests were performed comparing a particular embodiment ofthe filter media of the present invention to an existing electrostaticfilter. Each test was run in the same environment to treat air with adifferent contaminant. The experimental data provided was collectedduring these tests. In each of the tests a contaminant was introducedinto a chamber in a controlled amount and fed into four lines. Two ofthe lines included a filter according to the present inventioncomprising an electrostatically charged filter with an iodinated resinaccording the '452 patent incorporated thereto. The third line includedan electrostatically charged filter, known as Transweb. This filter doesnot have antimicrobial properties or any other type of active agentincorporated thereto. And a fourth line was provided as a control,having no filter and was used to confirm that the amount of contaminantentering the control chamber was equivalent to the amount of contaminantexiting the control chamber.

Exhibit A sets forth experimental data illustrating certain features ofexemplary embodiments of the present invention. Experiment No. AF276,describes the performance of different filtration membranes against BGspores for 30, 60, 120, 180, 240, 300, and 360 minutes of filtration. BGspores must be present in amounts of about 8,000 to 30,000 spores tocause illness in the average human. As can be seen in Exhibit A, foreach of the 30, 60, 120, 180, 240, 300 and 360-minute tests, the filterof the present invention achieved a 100% reduction of BG spores from theairstream.

As can be seen in Exhibit A, the electrostatic filter of the presentinvention achieves the essentially the same or similar net effect as theTransweb in these tests. However, an important advantage provided isthat the present invention sterilizes the spores rather than justholding the spores to the filter. Thus, unlike the present invention, ifthe Transweb is handled by a user or is contacted by the skin,contamination will occur. The present invention maintains the hygiene ofthe filter.

Turning now to Exhibit B, the results of Experiment AF270 there is showntest results for the performance of different filtration membranesagainst MS2 viruses for 30, 60, 120, 180, 240 300, and 360 minutes offiltration. Virus amounts ranging from 1 to 1000 viruses will causeillness in the average human. Thus, the presence of even one virus cancause illness in a human. As can be seen in Exhibit B, for each of the30, 60, 120, 180, 240, 300 and 360-minute tests, the filter of thepresent invention achieved a 100% reduction of MS2 viruses from theairstream. However, the Transweb does not achieve a 100% reduction inMS2 viruses and allows between 1000 to 10000 viral units to be found inthe effluent air stream. Use of Transweb to air contaminated with MS2viruses would not achieve desired results. Thus, as can be seen inExhibit B, in addition to the benefits of sterilization propertiesdescribed above with respect to Exhibit A, the present inventionprotects more effectively over viruses such as MS2 over time. Becauseonly a small amount of viruses contaminate a human (1 to 1000 viruses),unlike the present invention, Transweb does not effectively protect auser from these viruses.

CONCLUSION

Having now described one or more exemplary embodiments of the invention,it should be apparent to those skilled in the art that the foregoing isillustrative only and not limiting, having been presented by way ofexample only. All the features disclosed in this specification(including any accompanying claims, abstract, and drawings) may bereplaced by alternative features serving the same purpose, andequivalents or similar purpose, unless expressly stated otherwise.Therefore, numerous other embodiments of the additions and modificationsthereof are contemplated as falling within the scope of the presentinvention as defined by the appended claims and equivalents thereto.

1. A wound dressing, said wound dressing comprising: a protective mediafor filtering and killing microorganisms in air, said protective mediacomprising: a porous dielectric carrier, wherein said porous dielectriccarrier is a non-woven material; a biocidal active agent incorporated inor on said porous dielectric carrier, said active agent being aniodinated resin; and an electrostatic charge across at least a portionof said porous dielectric carrier.
 2. The wound dressing of claim 1 inwhich said porous dielectric carrier is a fiber based material having afibrous matrix structure.
 3. The wound dressing of claim 1 in which saidporous dielectric carrier is a sponge like material have an open cellmatrix structure, wherein the open cell matrix structure is a foam. 4.The wound dressing of claim 1 in which said non-woven material is athree dimensional structure configured to provide a matrix capable ofphysically entrapping said active agent.
 5. The wound dressing of claim4 in which said active agent is configured to be physically entrapped insaid matrix.
 6. The wound dressing of claim 1 in which said porousdielectric carrier comprises polymer fiber.
 7. The wound dressing ofclaim 6 in which said polymer fiber comprises a member selected from thegroup consisting of nylon, polyethylene, polyester, and polypropylene.8. The wound dressing of claim 1 in which said porous dielectric carrieris capable of holding an electrostatic charge in the presence of saidbiocidal active agent for at least six months.
 9. A wound dressing, saidwound dressing comprising: a first porous dielectric carrier; a firstactive agent incorporated in or on said first porous dielectric carrier,said first active agent being a biocidal iodinated resin; anelectrostatic charge across at least a portion of said first porousdielectric carrier; wherein said first porous dielectric carrier is anon-woven and capable of holding an electrostatic charge in the presenceof said biocidal iodinated resin; and a second porous dielectriccarrier; a second active agent incorporated in said second porousdielectric carrier.
 10. The wound dressing of claim 9, in which saidfirst active agent and said second active agent are of the samematerial.
 11. The wound dressing of claim 9 in which an air gapseparates said first and said second porous dielectric carriers.
 12. Thewound dressing of claim 9 in which each of said first porous dielectriccarrier and said second porous dielectric carrier is a fiber basedmaterial having a fibrous matrix structure.
 13. The wound dressing ofclaim 12 in which said fiber based material is a three dimensionalstructure configured to provide a matrix capable of physicallyentrapping said active agent.
 14. The wound dressing of claim 13 inwhich said active agent consists of particles configured to bephysically entrapped in said matrix.
 15. The wound dressing of claim 9in which said first porous dielectric carrier is capable of holding anelectrostatic charge in the presence of said biocidal iodinated resinfor at least six months.
 16. A protective liner, said protective linercomprising: a first porous dielectric carrier; a first active agentincorporated in or on said first porous dielectric carrier, said firstactive agent being a biocidal iodinated resin; an electrostatic chargeacross at least a portion of said first porous dielectric carrier;wherein said first porous dielectric carrier is a non-woven and capableof holding an electrostatic charge in the presence of said biocidaliodinated resin; and a second porous dielectric carrier; a second activeagent incorporated in said second porous dielectric carrier.